Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
doc sach » hoc sach, toc sach, nuoc sach
cham luc » cham soc, nhan luc, cham cuu
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
hieu va » hieu qua
luc va » duc va, tuc va, loc va
ban xa » ban va, ban ma, ban da
di cua » dai cua, doi cua, de cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((thuoc sach) or (doc sach)) van ban xa hoi. ((hieu va) OR (lieu va)) cham luc va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuoc sach) OR (doc sach)) van ban xa hoi. ((hieu va) OR (lieu va)) cham luc va hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuoc sach) or (doc sach)) van ban xa hoi. ((hieu va) OR (lieu va)) cham luc va hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thuoc sach) or (doc sach)) van ban xa hoi. ((hieu va) OR (lieu va)) cham luc va hanh di cua tre*.